gnupic: DIY USB programmer ?
Subject:
Re: DIY USB programmer ?
From:
Manuel Bessler ####@####.####
Date:
6 Jan 2005 17:37:39 +0000
Message-Id: <20050106183217.H27123@betazed3.varxec.de>
On Thu, Jan 06, 2005 at 07:19:42AM -0500, Byron A Jeff wrote:
> > The programmer should have sockets for at least 40/28pin pics and a ICSP
> > header. Like the olimex PG2C I mentioned before:
> > http://olimex.com/dev/pic-pg2c.html
>
> Bad idea. It's counter to your goal. This should definitely be an ICSP setup
> where you jumper to the target. It should be ICSP only.
>
> Remember it's going to get limited use. So there's no need to set it up as
> a traditional PIC programmer. Wiring different sockets is tough business.
> So make it ICSP only and remove that issue.
Thats why I said that I already have that. Olimex has a schematic after
which I did the layout. And I checked if those pin assignments are
half-way sane, and I believe they are (maybe not for a production
programmer, but ok for a prototype programmer).
> No. Keep it simple. A voltage doubler then requires a clock for the pump.
> It just makes it more complicated.
>
> 9V battery and snap, 12V zener, 2 resistors, switch. Simple. Wire the 9V
> so that the negative is on the 5V line giving 14V on the positive lead. Wire
> this through the series resistor. Then connect the zener between the other
> end of the resistor and ground. Wire this junction to one end of the switch
> and the other to MCLR. Use the second resistor as a pulldown on MCLR. Be
> sure that the zener resistor is at least 20 times lower value than the
> pulldown (i.e. 1K for the zener, 20K for the pulldown). Done. When the
> switch is open MCLR gets 0V. When the switch is closed MCLR gets 12V which
> is high enough for virtually every flash PIC.
>
> Keep it simple. It's a limited time use programmer.
I find that its often easier to use a wall wart power supply than to
find a 9V battery. just about every computer peripheral comes with a
power supply. If I need a 9V block battery, I never find one.
So, what about requiring a 9..15V power supply, a 555 charge pump for
upping the power to 15V, then a 7812 and 7805. That makes sure that
sufficient power is available.
Another homecockpit interface solution (not opensource, and
Win+MS FlightSim only) uses something like that. See here:
http://fsbus.de/img/FSCOM.GIF
This solution has the advantage that the PIC burning is built-in.
The user just has to jumper the to-be-burned board to 'program mode'.
Of course he has to write the programming algorithms into his flightsim
interface software. The hexfiles are also compiled into that program.
> > This would be a winner(-programmer) :)
>
> It's certainly worth testing. I may take a stab at it this weekend.
Looking forward to your findings.
Manuel
--
Opensource/Free Software: No Gates, No Windows
